Add font-size utilities based on Pajamas

app/assets/stylesheets/framework/common.scss

@@ -563,3 +563,10 @@ img.emoji {
 
 .gl-font-size-small { font-size: $gl-font-size-small; }
 .gl-line-height-24 { line-height: $gl-line-height-24; }
+
+.gl-font-size-12 { font-size: $gl-font-size-12; }
+.gl-font-size-14 { font-size: $gl-font-size-14; }
+.gl-font-size-16 { font-size: $gl-font-size-16; }
+.gl-font-size-20 { font-size: $gl-font-size-20; }
+.gl-font-size-28 { font-size: $gl-font-size-28; }
+.gl-font-size-42 { font-size: $gl-font-size-42; }

app/assets/stylesheets/framework/variables.scss

@@ -325,6 +325,12 @@ $gl-grayish-blue: #7f8fa4;
 $gl-gray-dark: #313236;
 $gl-gray-light: #5c5c5c;
 $gl-header-color: #4c4e54;
+$gl-font-size-12: 12px;
+$gl-font-size-14: 14px;
+$gl-font-size-16: 16px;
+$gl-font-size-20: 20px;
+$gl-font-size-28: 28px;
+$gl-font-size-42: 42px;
 
 $type-scale: (
   1: 12px,